1. Field of the Invention
This invention relates to telecommunications systems and, more particularly, to an apparatus and method for providing reduced length link setup signaling messages in a telecommunications system having a variable rate symmetric/asymmetric data channel.
2. Prior Art
Advances in the field of telecommunications have resulted in a variety of types of telecommunications systems being available for use by the general public. Among these telecommunications systems, cellular telephone networks are presently one of the most rapidly developing in terms of technologies and services offered. Cellular networks are currently in widespread use worldwide, with continued growth in sales and subscribers predicted for the foreseeable future.
Several types of technologies have become dominant in the cellular industry. In the United States most cellular systems currently operating use analog signal transmission techniques, as specified by the Telecommunications Industry Association/Electronic Industry Association(TIA/EIA) AMPS standard, or a combination of analog and time division multiple access (TDMA) signal transmission techniques, as specified by the TIA/EIA IS-54 and IS-136 standards. In Europe, cellular systems may operate according to one of several analog system standards, depending on the country, or according to the digital Global Services for Mobile (GSM) TDMA standard that has been specified for Europe. In other parts of the world most cellular systems operate according to one of the standards used in the United States or Europe, except for in Japan where the TDMA personal digital communication (PDC) standard has been developed and is in use. However, despite the present dominance of analog and TDMA technologies, the cellular industry is dynamic and new technologies are constantly being developed as alternatives to these currently dominant technologies. One alternative digital signal transmission technique that has recently been the focus of attention for cellular systems is known as code division multiple access (CDMA). In a CDMA system, multiple users, each using a channel identified by a uniquely assigned digital code, communicate with the system while sharing the same wideband frequency spectrum. CDMA provides several advantages over conventional analog or TDMA systems. For example, a CDMA system does not require frequency spectrum allocation planning for the mobile stations (MS) and the base stations (BS) of the cells, as with analog and TDMA systems, because all CDMA base stations share the entire downlink frequency spectrum, and all mobiles share the entire uplink frequency spectrum. The fact that the wideband frequency spectrum is shared by all uplink or downlink users in CDMA also increases capacity since the number of users that can be multiplexed simultaneously is limited not by the number of radio frequency channels available, but rather by the number of digital codes available to identify the unique communications channels of the system. Additionally, since the energy of the transmitted signals are spread over the wide band uplink or downlink frequency band, selective frequency fading does not affect the whole CDMA signal. Path diversity is also provided in a CDMA system. If multiple propagation paths exist, they can be separated as long as the differences in path delays does not exceed 1/BW, where BW equals the bandwidth of the transmission link. An example of a widely accepted cellular system CDMA standard is the TIA/EIA IS-95-A system specification.
Because data transmission applications other than conventional voice traffic transmission are becoming increasingly important in the wireless or cellular system area, a cellular system operator may desire to provide other services along with, or instead of, phone voice service on the system. Examples of these other services include portable computer cellular modem service or video service or the like which may also involve packet data. Often, these other services may require that data be transmitted at a rate much faster than that required for voice transmission. Hence, in the event that it is desired to provide a range of different services in a cellular system, it is useful to vary the data transmission rate in the system so that the data rate can be varied within a range required for all system services to provide both slower speed data transmission for efficient and reliable speech service and high speed data transmission for packet data and other applications. For example, the IS-95-A specified CDMA system is limited to a maximum data rate of 9600 bits per second (9.6 kbps) and it may be desirable to provide services in the IS-95-A system that require data transmission at rates greater than 9.6 kbps. It would also be desirable to provide services that allow the use of different data rates on each of the forward (base to mobile) and reverse (mobile to base) links. These same services would also be useful in other types of systems such as, for example, TDMA systems.
Problem to be Solved:
In high speed data and packet data applications there is a need to exchange much information about rate configuration during setup of the connection. This setup can require large signaling messages involving the rate configurations for the forward and reverse links. For example, the current IS-95 specification calls for the rate configuration for forward and reverse links to be encoded separately requiring a number of separate fields in the signaling messages. Consequently, connection setup poses a problem with regard to time and signal length. Also, a larger number of separate fields in the setup signaling messages requires more processing in both the mobile station and the base station.
Objects:
It is thus an object of the present invention to provide an improved high speed data rate service in a wireless or cellular phone system, such as a CDMA system.
It is another object of the invention to provide an apparatus and method for shortening the time and signal length required in the connection setup of such a system.
It is a further object of the invention to reduce the number of separate fields required in signal messages used in the connection setup of such a system, and to reduce the demand on processing resources and the processing time required in both the mobile station and the base station.
It is also an object of the invention to provide reduced length link setup signaling messages in a system having a variable rate symmetric/asymmetric data channel when the forward and reverse links of the data channel use the same data rate configuration.